Neurotransmitters are chemical messengers that transmit signals between nerve cells.
Nerves are composed of nerve cells. Nerves transmit the pain signal from the site of an injury to your spinal cord and up to your brain.
Along the way there are many connections between the nerves. It is the molecules that are released by one nerve cell and recieved by another nerve cell that transmits the pain signal between the nerves at each junction.
Your brain is a complex network of nerves and nerve cells that also use chemical messengers to communicate with each other.
Excitatory messengers stimulate the pain signal and make it sharper and faster. This sharpens your thinking and quickens your reflexes which help you escape danger quicker.
Inhibitory molecules will suppress the pain signal making it duller and slower and more tolerable allowing you to tolerate the pain and attend to other activities.
Scientists have identified over 50 different chemical molecules that act as messengers between your nerves and many more are known to exist but have not been well studied.
Neurotransmitters have their influence by interacting with receptors on the nerve cell surface.
Different nerve cells can have different receptors that may be activated by the same chemical messenger.
So the same molecule or messenger can cause different responses in different areas depending on which receptors it is stimulating.
Medications can manipulate the levels of these chemical in your system but these chemicals do not have the same effect in all parts of your body. So even if they cause a benefit in one area they may cause an undesirable response in another one of your bodies many systems.
Acetylcholine is the neurotransmitter that stimulates your skeletal muscles to move, but at your heart it acts to slow the heart muscle and reduce your heart rate. It does this by activating different receptors which causes different responses.
Changing how You Perceive the Pain
Serotonin, Dopamine, and GABA (gamma-Aminobutyric acid) are neurotransmitters that are found in your brain as well as many other locations. In your brain they influence your mood, feeling of pleasure and sense of well being, and all of these influences affect your perception of pain and how you feel about it.
Medications such as Duloxetine, Pramipexole and Diazepam have their effects by manipulating your levels of these chemical messengers.
However, side effects can occur when they stimulate receptors in other areas.
They may influence receptors in your stomach causing nausea. They may affect other receptors causing you to lose interest in sexual activities, or other receptors causing you to feel dizzy, or other receptors making you feel drowsy, or other receptors making you itch.
Your body is full of receptors and stimulating each one will cause a different response.
Enkephalins, Endorphins, and Dynorphins are some of your neurotransmitters that are involved in the perception of pain and the transmission of the pain signal. They activate opioid receptors that are located in your digestive tract, your spinal cord, and brain.
Narcotic medications, such as morphine and oxycodone, have their effect by blocking these opioid receptors, which suppresses the pain signal and the sensation of pain.
Side effects, such as sedation, respiratory depression, and constipation can occur when narcotics attach to other receptors throughout the body causing unintended consequences.
Every Treatment does not work for Every Person
Different medications work with different neuroreceptors and neurotransmitters to block or alter your sensation of pain at many different levels and in many different ways. Not all of these will work for every person because everyone's sensation of pain is different and every person’s combination of receptors is different.
If you completely avoid any medication that might cause side effects you will not have much hope of finding relief.
If you try a medication and it helps to control your pain but causes some other undesirable effect you will need to decide if the benefit is worth the problem it causes. Your doctor may be able to give you a medicine to control the side effects of the medicine you need to control your pain.
But, if the benefit is small and the problem it causes is large you should probably stop that medicine and try a different treatment.
All medications and all treatments come with risks. You should discuss with your doctor who knows you and your health history how the risks of a specific treatment relates to you.